Phase and polarity assessment of seismic data seg wiki. Zerophasing of seismic data request pdf researchgate. A number of standard interchange formats are used by amerada hess. Extraction of wavelet from seismic using a well log to determine the phase. May 19, 20 ah vibroseis and phase is a complicated animal.
Filters preserving phase in this chapter, linear phase and zero phase filters are defined and discussed. Fundamentals of seismic acquisition, processing and. Deconvolution during seismic processing can convert data of mixed phase to zero phase data, but is not always successful. Getting the most from seismic data in a perfect world, one person or a small team would design, oversee acquisition of, process, and interpret a seismic survey. Seismic data acquisition generation of artificial seismic signals on. Bibliography processing of seismic reflection data using. Receiver deghosting removing gr accounts for the fact that the seasurface reflects seismic energy back into the water layer such that any seismic event is recorded twice. May 27, 2014 in exploration for seismic stratigraphic interpretation the interpreter really needs to know is whether the data are processed to zero phase and whether the dominant loop in the resulting seismic. Is a phase change visible at the edge of the anomaly. Almost every seismic processing system will have its own format for seismic trace data, velocity files, horizon files etc. This attitude to the phase spectra of seismic signals can be explained by several facts. The reflection time for a zero phase wavelet is at the central peak or trough, so picking reflection times is much easier and accurate for zero phase wavelets. Figure 105a shows how the phase of this signal changes when it is shifted left or right. This barcode number lets you verify that youre getting exactly the right version or edition of a book.
Processing, inversion, and interpretation of seismic data, issue 10, volume 1 issue 10 of investigations in geophysics seismic data analysis. Seismic inverse q filtering is a data processing technology for enhancing the resolution of reflection seismology images. When interpreting seismic data it is important to realize that the actual subsurface geology is always being viewed through the filter of the seismic wavelet. In each case, several measures of length reveal that the zero phase wavelet is shorter than the minimum phase wavelet corresponding to the same amplitude spectrum.
The source of seismic waves is either an explosive which directly generates the seismic wavelet or a mechanical source which is commonly a vibrator, which uses a steel base plate in contact with the ground. A source signature was modelled to pass through the various processing stage, the resulting output converted to zero phase and the operator applied to the seismic data. At the highest frequency, onehalf of the sampling rate, the phase increases by. Does the flat spot have the correct zero phase character. Resolution comparison of minimumphase and zerophase signals. A zerophase signal is thus a linearphase signal for which the phaseslope is zero.
Though dipazimuth and shaded relief are identical attributes, they look quite different figure 9. For several amplitude spectra typical of processed seismic sections, both minimumphase and zerophase wavelets are presented. How can i determine the phase of processed 2d seismic data. Aspects of seismic reflection data processing book, 1990. Borehole seismic data processing and interpretation. By contrast, this course uses cartoons and real data examples to provide an intuitive understanding of the seismic processing procedures. The topics include data sets from shear waves, which, generated by mode conversion, are used in solving reservoir problems. The actual seismic data around the well shows many of the effects we ve. Aug 21, 2003 3d seismic data have become the key tool used in the petroleum industry to understand the subsurface. Have the seismic data being used been converted to zero.
Zerophase signals are discussed in sheriff and geldart, 1995, section 15. Non zero phase wavelets are converted to zero phase wavelets to achieve the best resolution of the seismic data. The desired output wavelet is designed to preserve the. The solutions to these problems are to convert the mixedphase wavelet to zero phase in seismic processing or to extract the mixedphase wavelet, know its effects, and use it when modeling. Zerophase signals are discussed in sheriff and geldart, 1995, section. Deghosting and designature removing the seismic ghost. Having our data in the first condition is preferable because it minimizes processing and ambiguity, but the second one might lead to counting false events as true reflections andor distort actual events see figure 1. The desired output processing wavelet is derived from a zero phase equivalent of the modeled instrument response which is tapered to match the natural decay of the farfields amplitude spectrum. Phase and amplitude distortions to the seismic signal, the physical. In exploration for seismic stratigraphic interpretation the interpreter really needs to know is whether the data are processed to zero phase and whether the dominant loop in the resulting seismic. Hence data processing today makes every effort to deliver the data in a zerophase condition.
Relies on signal being in phase and noise being out of phase i. Known zero phase well synthetics and vertical seismic profiles vsps can be compared with local surface seismic data to. How do we convert the seismic trace wavelet to zero phase. Understanding seismic detection and resolution of high. Practical solutions to integrated oil and gas reservoir analysis pp. From the acoustic impedances produced by seismic inversion, the authors derive seismic. How to remedy nonoptimal seismic data by seismic processing. We know that achieving a zerophase wavelet is difficult, and thus it would be helpful if authors in this journal provide a comment on the phase of the data they are presenting in their interpretations. Seismic data processing is a course designed to provide students with. Seismic processing this group type is used for document loading only.
Seismic data processing investigations in geophysics, vol. Nonzerophase wavelets are converted to zerophase wavelets to achieve the best resolution of the seismic data. Is the phase change structurally consistent and at the same level as the flat spot. The seismicdata processing consists of velocity modeling, wavelet processing, and seismic inversion. Zerophase data tend to provide sharper definition and less distortion between stratigraphic features in the subsurface, such as sand and shale layers. Seismic amplitude calibration for quantitative interpretation.
Seismic data processing schemes are then introduced to explain the significance associated with seismic processing stages to obtain a good seismic section. In each case, several measures of length reveal that the zerophase wavelet is shorter than the minimumphase wavelet corresponding to. Request pdf zerophasing of seismic data by zerophasing the. Characteristics of the phase digital signal processing. Is the flat spot located at the down dip limit of brightness or dimness. A seismic line processed with a cosine of the phase, and with b a strong agc using a 28 ms window 7 samples. Center for wave phenomena colorado school of mines golden, co 80401, usa past support was received from. Commonly zero phase wavelet is used to interpretation seismic data because the wavelet has highest sn than other, maximum amplitude coincides with spike of reflection, and the pattern of wavelet is symmetry so picking horizon become easy. Linear phase filters symmetric impulse responses a linear phase filter is typically used when a causal filter is needed to modify a signals magnitudespectrum while preserving the signals timedomain waveform as much as possible. We know that achieving a zero phase wavelet is difficult, and thus it would be helpful if authors in this journal provide a comment on the phase of the data they are presenting in their interpretations.
Shape the source wavelet to zero phase or minimum phase, depending on your application. Since some years the deterministic approach for processing shows many advantages. Fred schroeder, retired from exxonexxonmobil presented on august 24, 2017. Processing, inversion, and interpretation of seismic data, ozdogan yilmaz, isbn 1560800941, 9781560800941. Dec 23, 2015 ali added it dear sir ozdogan, i need to your book seismic data processing, if. View chapter purchase book 2d and 3d seismic data t. A reprinting of eight articles from surveys in geophysics, v. Zero phase data tend to provide sharper definition and less distortion between stratigraphic features in the subsurface, such as sand and shale layers. Data conditioning encompasses a wide range of technologies designed to address numerous challenges in the processing sequencefrom data calibration and regularization. Q is the anelastic attenuation factor or the seismic quality factor, a measure of the energy loss as the seismic wave moves. This is the ideal of seismic imaging flat surface and collocated sources and receivers in practice, multifold, offset recording is used, and zerooffset section is obtained by extensive data processing. The reflection time for a zerophase wavelet is at the central peak or trough, so picking reflection times is much easier and accurate for zerophase wavelets. All too often, an offtheshelf design is shot by a lowbid contractor, processed with standard flow and parameters, then delivered for interpretation. The objective of the statistical and deterministic deconvolution short course is to familiarize exploration seismologists about the theory and practice of seismic deconvolution and zero phase seismic processing.
Seismic data acquisition and processing springerlink. It must be that in 1993 were much better at getting a zerophase section than we were in. Indeed, these assumptions are central to most avo and other quantitative work. When interpreting seismic data, it is important to realize that the actual subsurface geology is always being viewed through the filter of the seismic wavelet. Seismic data processing investigations in geophysics, vol 2 by ozdogan yilmaz author, stephen m. Seismic data processing geos 469569 spring 2006 geos 469569 is a mix of digital filtering theory and practical applications of digital techniques to assemble and enhance images of subsurface geology. In seismic data processing we generally assume that the acquired seismic data is a minimum phase and that after deconvolution the data is now zero phase. Filters preserving phase introduction to digital filters.
It is easy to compute its zero phase equivalent f and design a shaping filter g that converts the minimum phase wavelet e to the zero phase wavelet f. Thus, information about the phase spectrum of the observed signal is lost or substantially distorted. Digital filtering theory applies to virtually any sampled information in time e. Pertaining to seismic data whose wavelet is symmetrical about zero time. The society of exploration geophysicists the gas research institute. Hence data processing today makes every effort to deliver the data in a zero phase condition. Resolution comparison of minimumphase and zerophase. Note that in seismic, the cosine wave is the sinusoid of reference since it is a maximum at time.
Seismic surveys are conducted by deploying an array of energy sources and an array of sensors or receivers in an area of interest. Applicationspecific seismic data conditioning and processing for confident imaging from the field to the final volume, seismic data goes through many processes and workflows. Seismic data are usually processed to be zero phase, and we usually assume that the phase is stable in space and time. The solutions to these problems are to convert the mixed phase wavelet to zero phase in seismic processing or to extract the mixed phase wavelet, know its effects, and use it when modeling. Zero phasing converts the signal to one with zerophase. The overall objective of this course is to introduce entry level andor junior geophysicists and geoscientists to the essential acquisition and technical processing concepts and principles that form the basis for value added seismic applications in exploration, field appraisal, and reservoir. Aspects of seismic reflection data processing social sciences. Along with amplitude and frequency, phase is a fundamental attribute of seismic data. Topics reflection and avo simple imaging concept of zerooffset migration role of velocity in migration. A zero phase signal is thus a linear phase signal for which the phase slope is zero. Deghosting and designature removing the seismic ghost and.
Deconvolution during seismic processing can convert data of mixed phase to zerophase. My preferred way of doing this ive been working in seismic data processing and analysis for over 20 years now is. This is one reason why zerophase wavelets are usually output in seismic data processing. Because the imaginary part is zero, the phase is zero. Early in our careers as geophysicists, most of us took at least one course on seismic signal analysis where we were taught that standard wiener deconvolution converts the minimum phase source wavelet in our seismic data to a wavelet with a phase spectrum that is zero and an amplitude spectrum that. The inverse of the operator d is the minimum phase wavelet e, which is sometimes assumed to be the basic wavelet contained in the original seismic trace. The overall objective of this course is to introduce entry level andor junior geophysicists and geoscientists to the essential acquisition and technical processing concepts and principles that form the basis for value added seismic applications in exploration, field appraisal, and reservoir management. The seismic data processing consists of velocity modeling, wavelet processing, and seismic inversion. For several amplitude spectra typical of processed seismic sections, both minimum phase and zero phase wavelets are presented. Aspects of seismic reflection data processing social. Transforming mixed phase to minimum phase wavelets, roots, double. Dec 15, 2016 principles of seismic data processing m.
Seismic data processing mostly takes into account the statistics inherent in the data to improve the data quality. Zero phase signals are discussed in sheriff and geldart, 1995, section 15. Deconvolution during seismic processing can convert data of mixed phase to zerophase data, but is not always successful. Wavelet polarity is divided to be 2 that is the europe standard and seg standard. The desired output wavelet is designed to preserve the total energy of the farfield signature. In addition to providing excellent structural images, the dense sampling of a 3d survey makes it possible to map reservoir quality and the distribution of oil and gas. For example, consider a waveform that is symmetrical around sample zero, and therefore has a zero phase.
Jones abstract conventional seismic data processing, whether it be prestack data conditioning or migration, is designed with the theory of pwave reflected energy inmind, for travel paths involving only a single reflection. Zerophase filtering of a minimumphase wavelet seg wiki. The subsequent section on seismic interpretation is focused on introducing the method of translating the observed seismic sections to geological information critical to hydrocarbon exploration. Zero phase wavelets are symmetrical in shape about zero time whereas non zero phase wavelets are asymmetrical.
For the earth response, aki and richards state in their book quantitative. Topics to be covered include statics corrections, filtering, velocity analysis, deconvolution, stacking and migration. First, there exists certain traditionalism in using seismic arrival times in the data processing. This is one reason why zero phase wavelets are usually output in seismic data processing. Vertical seismic profile as a phase tool the fresnel zone improving spatial resolution improving resolution of depth estimation sample processing sequences ramifications of processing decisions noise. Seismic statistical and deterministic deconvolution course. Zerophase wavelets are symmetrical in shape about zero time whereas nonzerophase wavelets are asymmetrical.93 914 632 1295 1065 212 1407 349 321 465 398 277 1250 787 400 187 764 945 1190 739 56 63 604 1212 1298 1133 217 1198 1442 689 237 237 1114 1013 670 4 991 1418